So you dangled the bait at the end of book one, perfectly set up that secondary character or the next scenario.  Now it’s time for book two.  And suddenly you realize–writing a sequel is hard

The best sequels tease the reader with hints of a possible previous story, but don’t make it feel as though you had to have read that first book to enjoy the second.  The characters are naturally developed without a lot of explanation.

The worst sequels start with info dump on everything you missed–kind of a “let me catch you up” chapter at the beginning of the book.  Not only do you feel as though you’re starting in the middle, but now you also know how the first book ends, so what’s the sense in going back to read it?

Every book in a series needs to stand on its own.  Authors have to assume that each book is the reader’s introduction to these characters.  It doesn’t mean you need every single background detail, but it is good to remind readers who the major players are and how they’re related.  

Each book also has to represent its intended genre.  If you’re proposing a romance series, there should be a development of the relationship in each book; you can’t wait until book three to get the romance going.  If you’re writing a Western about a continuing character, he needs to be in the West in book one.

Once readers fall in love with certain characters, it’s hard to let them go.  That’s why series are so popular.  But finding that balance between attracting new readers and keeping the old is not an easy job.